3D flow in subduction zones: Implications for slab...
Transcript of 3D flow in subduction zones: Implications for slab...
![Page 1: 3D flow in subduction zones: Implications for slab ...geoprisms.org/wp-content/uploads/2015/02/Alaska2011...3D generalization of 2D benchmark (van Keken et al., 2008) What is the best](https://reader033.fdocuments.us/reader033/viewer/2022053119/60a0b2df7d5df0417367a725/html5/thumbnails/1.jpg)
3D flow in subduction zones: Implications for slab temperature and seismic anisotropy
Peter van Keken, University of Michigan
Geoprisms Alaska Planning meeting Portland, OR, September 2011
Phot
o by
Ikuk
o W
ada
![Page 2: 3D flow in subduction zones: Implications for slab ...geoprisms.org/wp-content/uploads/2015/02/Alaska2011...3D generalization of 2D benchmark (van Keken et al., 2008) What is the best](https://reader033.fdocuments.us/reader033/viewer/2022053119/60a0b2df7d5df0417367a725/html5/thumbnails/2.jpg)
With thanks to: Geoff Abers, Brad Hacker, Ellen Syracuse, Amy Bengtson, Jun Nakajima, Saeko Kita
Phot
o by
Juli
Mor
gan
![Page 3: 3D flow in subduction zones: Implications for slab ...geoprisms.org/wp-content/uploads/2015/02/Alaska2011...3D generalization of 2D benchmark (van Keken et al., 2008) What is the best](https://reader033.fdocuments.us/reader033/viewer/2022053119/60a0b2df7d5df0417367a725/html5/thumbnails/3.jpg)
Thermal structure of slabs oblique convergence & arcuate trenches
EQ sensitivity to thermal structure 3D flow around/near slab edges
Phot
o by
Juli
Mor
gan
![Page 4: 3D flow in subduction zones: Implications for slab ...geoprisms.org/wp-content/uploads/2015/02/Alaska2011...3D generalization of 2D benchmark (van Keken et al., 2008) What is the best](https://reader033.fdocuments.us/reader033/viewer/2022053119/60a0b2df7d5df0417367a725/html5/thumbnails/4.jpg)
Bengtson and van Keken, in prep.
Two simple 3D geometries
![Page 5: 3D flow in subduction zones: Implications for slab ...geoprisms.org/wp-content/uploads/2015/02/Alaska2011...3D generalization of 2D benchmark (van Keken et al., 2008) What is the best](https://reader033.fdocuments.us/reader033/viewer/2022053119/60a0b2df7d5df0417367a725/html5/thumbnails/5.jpg)
3D generalization of 2D benchmark (van Keken et al., 2008)
What is the best choice for 2D cross section in the case of oblique subduction?
Vx < Vs γ > γ’
![Page 6: 3D flow in subduction zones: Implications for slab ...geoprisms.org/wp-content/uploads/2015/02/Alaska2011...3D generalization of 2D benchmark (van Keken et al., 2008) What is the best](https://reader033.fdocuments.us/reader033/viewer/2022053119/60a0b2df7d5df0417367a725/html5/thumbnails/6.jpg)
Oblique convergence in 3D: which 2D cross section is appropriate? Angle θ = 60 degrees; isoviscous
T (C) at slab depth: 60 km 100 km 200 km 3D results 442 614 747 2D trench normal 439 613 746 2D velocity parallel 350 549 681
![Page 7: 3D flow in subduction zones: Implications for slab ...geoprisms.org/wp-content/uploads/2015/02/Alaska2011...3D generalization of 2D benchmark (van Keken et al., 2008) What is the best](https://reader033.fdocuments.us/reader033/viewer/2022053119/60a0b2df7d5df0417367a725/html5/thumbnails/7.jpg)
Oblique convergence in 3D: which 2D cross section is appropriate? Angle of 60 degrees; diffusion-creep (T-sensitive)
T (C) at slab depth: 60 km 100 km 200 km 3D results 577 703 787 2D trench normal 577 703 786 2D velocity parallel 529 654 733
![Page 8: 3D flow in subduction zones: Implications for slab ...geoprisms.org/wp-content/uploads/2015/02/Alaska2011...3D generalization of 2D benchmark (van Keken et al., 2008) What is the best](https://reader033.fdocuments.us/reader033/viewer/2022053119/60a0b2df7d5df0417367a725/html5/thumbnails/8.jpg)
oblique convergence in arcuate trenches (Marianas, Aleutians)
![Page 9: 3D flow in subduction zones: Implications for slab ...geoprisms.org/wp-content/uploads/2015/02/Alaska2011...3D generalization of 2D benchmark (van Keken et al., 2008) What is the best](https://reader033.fdocuments.us/reader033/viewer/2022053119/60a0b2df7d5df0417367a725/html5/thumbnails/9.jpg)
Speed (cm/yr)
5 cm/yr
Bengtson and van Keken, in prep.
full olivine rheology (stress, T-dependent)
![Page 10: 3D flow in subduction zones: Implications for slab ...geoprisms.org/wp-content/uploads/2015/02/Alaska2011...3D generalization of 2D benchmark (van Keken et al., 2008) What is the best](https://reader033.fdocuments.us/reader033/viewer/2022053119/60a0b2df7d5df0417367a725/html5/thumbnails/10.jpg)
Bengtson and van Keken, in prep.
![Page 11: 3D flow in subduction zones: Implications for slab ...geoprisms.org/wp-content/uploads/2015/02/Alaska2011...3D generalization of 2D benchmark (van Keken et al., 2008) What is the best](https://reader033.fdocuments.us/reader033/viewer/2022053119/60a0b2df7d5df0417367a725/html5/thumbnails/11.jpg)
Central Alaska
EQs follow Clapeyron slope 0.1 MPa/K (Abers et al., 2006)
![Page 12: 3D flow in subduction zones: Implications for slab ...geoprisms.org/wp-content/uploads/2015/02/Alaska2011...3D generalization of 2D benchmark (van Keken et al., 2008) What is the best](https://reader033.fdocuments.us/reader033/viewer/2022053119/60a0b2df7d5df0417367a725/html5/thumbnails/12.jpg)
Kita et al., 2006
Tohoku
![Page 13: 3D flow in subduction zones: Implications for slab ...geoprisms.org/wp-content/uploads/2015/02/Alaska2011...3D generalization of 2D benchmark (van Keken et al., 2008) What is the best](https://reader033.fdocuments.us/reader033/viewer/2022053119/60a0b2df7d5df0417367a725/html5/thumbnails/13.jpg)
Serpentinized peridotite
Anhydrous peridotite
eclogite
blueschist
greenschist
Temperature and metamorphic facies following van Keken et al., 2010
Tohoku
![Page 14: 3D flow in subduction zones: Implications for slab ...geoprisms.org/wp-content/uploads/2015/02/Alaska2011...3D generalization of 2D benchmark (van Keken et al., 2008) What is the best](https://reader033.fdocuments.us/reader033/viewer/2022053119/60a0b2df7d5df0417367a725/html5/thumbnails/14.jpg)
Tohoku
![Page 15: 3D flow in subduction zones: Implications for slab ...geoprisms.org/wp-content/uploads/2015/02/Alaska2011...3D generalization of 2D benchmark (van Keken et al., 2008) What is the best](https://reader033.fdocuments.us/reader033/viewer/2022053119/60a0b2df7d5df0417367a725/html5/thumbnails/15.jpg)
Long and Becker, 2010
Jadamec and Billen, 2010
Flow around slab edges
![Page 16: 3D flow in subduction zones: Implications for slab ...geoprisms.org/wp-content/uploads/2015/02/Alaska2011...3D generalization of 2D benchmark (van Keken et al., 2008) What is the best](https://reader033.fdocuments.us/reader033/viewer/2022053119/60a0b2df7d5df0417367a725/html5/thumbnails/16.jpg)
Buttles and Olson, 1998
![Page 17: 3D flow in subduction zones: Implications for slab ...geoprisms.org/wp-content/uploads/2015/02/Alaska2011...3D generalization of 2D benchmark (van Keken et al., 2008) What is the best](https://reader033.fdocuments.us/reader033/viewer/2022053119/60a0b2df7d5df0417367a725/html5/thumbnails/17.jpg)
Jadamec and Billen, 2010
![Page 18: 3D flow in subduction zones: Implications for slab ...geoprisms.org/wp-content/uploads/2015/02/Alaska2011...3D generalization of 2D benchmark (van Keken et al., 2008) What is the best](https://reader033.fdocuments.us/reader033/viewer/2022053119/60a0b2df7d5df0417367a725/html5/thumbnails/18.jpg)
Kneller and van Keken, 2008
![Page 19: 3D flow in subduction zones: Implications for slab ...geoprisms.org/wp-content/uploads/2015/02/Alaska2011...3D generalization of 2D benchmark (van Keken et al., 2008) What is the best](https://reader033.fdocuments.us/reader033/viewer/2022053119/60a0b2df7d5df0417367a725/html5/thumbnails/19.jpg)
Christensen & Abers, 2010 Bellesiles et al., in prep.
1 second